The phrase "former founder" refers to someone who was previously a founder or creator of a company or organization, but is no longer involved with it. Full definition
The Entrepreneur Richard Rosenblatt, CEO of WhipClip, former founder of Demand Media, Intermix The Mentor Gordon Crawford, media investor (entrepreneur.com)
Again, on the surface of things I know this sounds wonderful to entrepreneurs and of course I read all the the tropes about «how VC is dead» and is going to be replaced by a roving band of altruistic former founders sprinkling funding dust on startups. (inc.com)
I have never heard of a co-sale right actually being used, although I know that lots of companies remind former founders about their ROFR obligations. (startupcompanylawyer.com)